Diastereomeric benzylmethylphenyltelluronium salt was synthesized and optically resolved into the respective optical isomers. The absolute configurations of the isomers were determined by X-ray analysis of the (−)-isomer. Enantiomeric telluronium salts were also obtained by anion-exchange reactions of the diastereomeric isomers. Optically active telluronium bromide was found to racemize in solution and the racemization was indicated to occur through the elimination of benzyl bromide.

Diastereomeric benzylmethylphenyltelluronium (1S)‐(+)‐ and (1R)‐(–)‐camphor‐10‐sulfonates were synthesized and resolved by fractional recrystallization. The absolute configurations of the isomers were determined by X‐ray crystallographic analysis. Enantiomerically pure telluronium salts with achiral counteranions, such as tetrafluoroborate, 4‐chlorobenzenesulfonate, bromide, iodide, and tetraphenylborate, were also obtained by anion‐exchange reactions of the separated diastereomers. The optically active telluronium salts possessing counteranions with a high nucleophilicity, such as bromide and iodide, were found to racemize in solution. The racemization of the telluronium salts was found to proceed either through the formation of a tellurane by the nucleophilic addition of a counteranion to the tellurium atom followed by decomposition into methyl phenyl telluride and benzyl halide or by several pseudorotations of the tellurane.